IN his first major speech as Scottish Labour leader, Jim Murphy brought the house down.

The applause was not for the benefit of the TV cameras - there was a feeling of buoyancy in the air that suggested the members of the party faithful who crammed into a small room in Glasgow's City Halls two days after his victory truly believed they had turned a corner.

He said it wouldn't be easy to beat the SNP, that it would take hard work, grit and pounding the pavements like never before. But they lapped up every word and perhaps for the first time in a long time, there was a determined confidence in the air - Labour were going to take on the SNP and they were going to win.

Just a week later, a reality check arrived in the form of a Survation poll, out yesterday. The first major survey carried out since Mr Murphy was elected leader, it showed Labour's support stagnant on 24 per cent in terms of voting intentions for May's general election. The SNP's, meanwhile, rose slightly to hit double that figure.

Murphy, with some justification, pointed out that he had only been in the job a week. His key message - that the party is desperate to change and the argument that a vote for the SNP is a vote to let David Cameron back in to Downing Street - will take time for voters to switch on to.

But what may be more worrying for Labour is are the findings on Murphy himself. Almost one in five voters (18 per cent) said his election made them less likely to back Labour, compared to 14 per cent who said it was more likely. It was a 'reverse honeymoon', as the SNP described it. According to polling expert John Curtice, the findings showed Murphy was no 'magic bullet' for the Labour cause.

It raised a question that had largely been dormant since that barnstorming first speech a week previously - how likely voters are to be turned off Labour by the new leader?

Neil Findlay's campaign believed that polarising nature of the frontrunner among party members could catapult the MSP to victory. They were wrong but the assessment of one insider - that "Genghis Khan was more left wing than Jim" - gives an indication of how he is viewed by some of his colleagues.

The SNP, meanwhile, believe that Murphy is unlikely to win back the 'red nats' - traditional Labour voters who backed independence - and therefore struggle to find mass appeal.

They add that what many saw as a coronation of Murphy meant that Labour has not had a serious debate about where it went wrong in the past.

His status as an MP, campaigning alongside the Tories during the referendum campaign, previous backing for the Iraq War and the renewal of Trident are all seen by the SNP lines of attack that will resonate with traditional Labour voters in the Westminster and 2016 Holyrood election campaigns.

Jim Murphy has overcome the odds before, not least by turning a safe Tory seat into a Labour stronghold before rising to the UK cabinet. His latest challenge is his most daunting yet.